Peter Dollond, the subject of the present memoir, was the eldest son of John Dollond, the celebrated inventor of the Achromatic Refracting Telescope, who, during the greater portion of his life, was engaged in the business of a silk-manufacturer, in Stuart Street, Spitalfields. Here Peter Dollond was born and spent the early portion of his life. On reaching manhood he engaged in the same occupation as his father, and for several years they carried on their manufactures together in Spitalfields. Peter Dollond had, however, acquired some knowledge of the theory of Optics, and he determined, if possible, to turn the knowledge he had gained to the improvement of himself and his family. He accordingly commenced business as an optician, under the direction of his father, in the year 1750, occupying a small house in Vine Street, Spitalfields. In 1752 John Dollond, who up till then had pursued his original occupation, grew weary of pursuits so little in accordance with the natural bent of his mind, and entered into partnership with his son, in a house near to Exeter Change, in the Strand. Here father and son began and continued that series of experimental researches which, in June 1758, led to the memorable conclusion on which was founded the construction of the Achromatic Refracting Telescope. In the following year a patent was obtained for the exclusive sale of these telescopes, but so limited were the means of the authors of this invention, that, in order to defray the expenses of the patent, they were compelled to sell a moiety of its value to an optician, with whom they entered into partnership. Notwithstanding the great practical value of this discovery, it produced little benefit for some years to the owners of the patent. In 1761 John Dollond died, leaving to his son Peter the task of carrying on the business in partnership with the optician who had paid for the patent. This connection was, however, of short duration, for the conduct of his partner was so unsatisfactory, that in 1763 Mr. Dollond purchased from him his share in the business for 200_l._, the full commercial value of this most important discovery being considered at that time to be worth only 400_l._ Peter Dollond was now in possession of the entire patent, and he was soon called upon to contest its validity with the very man who had so lately been concerned in protecting it. These suits were uniformly decided in favour of Dollond, and although vexatious in their character, were of advantage to him, not only in their immediate issue, but also in extending the name, reputation, and sale of the object whose right of ownership was contested.